Flume or weir continuous water flow rate recorder for irrigation use

US Bureau of Reclamation projects and irrigation districts need simple, low‐cost, robust devices to measure and record water use for effective water management decisions. This need has resulted in the development of a continuous flow meter and recorder (CFM). The CFM is designed to continuously measure flow rates through open channel measurement structures, such as flumes or weirs, by recording the water levels upstream. The water level measurements are then converted to flow rate using a simple weir power equation. The CFM consists of an easily programmed CPU, an LCD for displaying the flow rate and total amount of water that has passed through the measurement structure, and a water level sensor. The CFM, including a solar power supply, may be purchased for under US$1000. The majority of that cost is for the water level sensor and may be reduced depending upon the needed accuracy. Presently, some of these devices have been installed on irrigation systems in the field where they have been exposed to harsh weather conditions. Despite the harsh environments, the CFMs have been functioning as designed. This paper discusses the design, installation, and testing of the continuous flow meter. Published in © 2005 John Wiley & Sons, Ltd.